This invention relates to an apparatus for processing photosensitive material, in particular it relates to the insertion and removal of the photosensitive material from the apparatus.
In many processors it is necessary to pull the film out of the film cassette or a loading station prior to the film being fed into processing tanks. To prevent damage to the film it is usual to manually attach a leader card to the leading edge of the film. The pulling and guiding forces as the film passes through the processor are then applied to the leader card instead of to the film itself. These leader cards are normally made of a robust flexible plastics material. As they are used they become damaged and therefore they need to be inspected before they can be re used. It is therefore not possible to use these leader cards in kiosk type processors where there is no operator and where the films are automatically withdrawn and fed into the processor. It is also not possible to use these leader cards in processors such as that disclosed in U.S. patent application Ser. No. 09/920,495, now U.S. Pat. No. 6,505,979, where the film is fed around a narrow path by drive rollers.
To overcome the above mentioned problems, and to provide a positive drive to load and unload the film from a processor a sprocket wheel system has been devised.
According to the present invention there is provided an apparatus for processing photosensitive material comprising a rotatable outer drum and an inner sprocket wheel independently rotatable from the outer drum, the inner wheel being provided with at least two sets of sprocket teeth for engagement with a strip of material to be processed, two pairs of drive rollers being located around the outer periphery of the drum.
Preferably one set of teeth are spring loaded.
The processor provides a positive drive system for loading and unloading the film. The film is held in position throughout the process and is therefore less likely to be damaged. The film is held in both dry and wet conditions. The pitch of the film does not have to be totally accurate to load into the processor. This allows for variances in the pitch due to film swell or manufacture. During processing there is no relative movement between the outer drum and the inner sprocket wheel. Thus there is no sticking or jamming.